"Closed captioning allows persons with hearing disabilities to have access to television programming by displaying the audio portion of a television program as text on the television screen." (includes important sound effects and labels of who is doing the speaking) ~http://www.fcc.gov/guides/closed-captioning
Subtitles
"Aimed at those who can hear, but not necessarily understand the language." (No sound effects or labels, usually used for foreign films) ~Captions vs subtitles - alastairc.ac
Closed Captions
~http://www.fcc.gov/guides/closed-captioning
Subtitles
~Captions vs subtitles - alastairc.ac
Articles and Background Info:
Getting Started with Video Captioning by Patrick Besong (PDF)
Understanding Captions & Subtitles - SCREENFONT.CA
Caption it Yourself - Basic Guidelines and Great Examples
FREE
**Paid Version $2.99
iCab Mobile (Web Browser)FREE
Closed Caption your Videos with Discovery Education